diff --git a/src/lib.rs b/src/lib.rs
index ec19563..5517302 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -37,3 +37,39 @@ pub fn tokenize<'a>(
 > {
     lexer::Tokenizer::new_with_errors(bytes)
 }
+
+trait BitSize {
+    fn bits(&self) -> u32;
+}
+
+macro_rules! impl_bitsize_int {
+    ($($ty:ty)*) => {
+
+        $(
+impl BitSize for $ty {
+    fn bits(&self) -> u32 {
+        Self::BITS as u32 - self.trailing_zeros() as u32
+    }
+})*
+    };
+}
+
+impl_bitsize_int!(u8 u16 u32 u64 u128);
+
+impl BitSize for &[u8] {
+    fn bits(&self) -> u32 {
+        let bytes = self.as_ref();
+        let mut bits = bytes.len() * u8::BITS as usize;
+
+        for &d in bytes.iter().rev() {
+            if d == 0 {
+                bits -= u8::BITS as usize;
+            } else {
+                bits -= d.leading_zeros() as usize;
+                break;
+            }
+        }
+
+        bits as u32
+    }
+}